The present invention relates to a timing gear assembly for a trochoidal rotary expansible chamber device having a planetating rotor inwhich a dual set of timing gears are provided on opposite sides of the rotor to prevent rotor wobble.
Trochoidal rotary expansible chamber devices, such as the Wankel or epitrochoidal rotary machines, generally comprise a housing defining a cavity in which is mounted a rotor rotatable in a planetating fashion. Trochoidal rotary devices may be divided into two groups referred to as inner envelope and outer envelope types. In an inner envelope configuration, the profile of the housing cavity is the trochoidal curve and the peripheral profile of the rotor is the inner envelope of the trochoidal curve. In an outer envelope device, the rotor profile is the trochoidal curve and the housing cavity profile is the outer envelope of that curve. Variable spaces formed between the facing peripheral surfaces of the rotor and the housing cavity serve as working chambers for fluid compression or expansion.
A chronic problem in trochoidal devices is rotor wobble. Rotor wobble is the result of cantilevering of the rotor in its planetating movement and is especially pronounced in outer envelope devices in which a pinion timing gear connected to the rotor moves about a ring gear. Rotor wobble is likely the result of the radial demeshing force applied against the beveled surface of the pinion gear teeth by its movement about the ring gear.
Rotor wobble can cause power loss and working chamber inefficiencies. Rotor wobble primarily causes the peripheral edges of the rotor to dig into the sidewalls, causing material degradation and premature failure of the device.
This wobbling action causes uneven seal wear in the rotor housing, which is more pronounced with greater seal area and rotor size, and results in lower seal life for the trochoidal device.